Netherlands 1930, first flight Airmail cover FFC from the Hage in the Netherlands to Zagreb Croatia.  Philatelic reused at the 5th International Congress on Air Navigation held in the Ridderzaal at The Hague, from 1 to 6 September 1930. Postmarked In January 24, 1930.  received at the  Zagreb consulate - back postmark.This card was first cancelled at Aug. 24th, 1929 - 'Conference de la Haya' and re used one year later for the first flight Amsterdam to Zagreb, correct additional postage was added.